Over the past decade, I’ve asked around 2,000 of the oldest Americans about their practical advice for living. One big question I posed to them was: What do you regret, and how can young people reach the end of life without major regrets? I expected big-ticket items: an affair, a shady business deal, addictions — that kind of thing. I was therefore unprepared for the answer they often gave:

I wish I hadn’t spent so much of my life worrying.

Over and over, as the elders in my Legacy Project reflected on their lives, I heard versions of “I would have spent less time worrying” and “I regret that I worried so much about everything.” Their advice on this issue is devastatingly simple and direct: Worry is an enormous waste of your precious and limited lifetime.

John Alonzo, 83, is a man of few words, but I quickly learned that what he had to say went straight to the point. A construction worker, he had battled a lifetime of financial insecurity. But he didn’t think twice in giving this advice:

“Don’t believe that worrying will solve or help anything. It won’t. So stop it.”

That was it. His one life lesson was simply to stop worrying.

The elders see worry as a crippling feature of our daily existence and suggest that we do everything in our power to change it. Why is excessive worry such a big regret? Because, they tell us, worry wastes your very limited and precious lifetime. By poisoning the present moment, you lose days, months, or years that you can never recover.

Betty, 76, expressed this point with a succinct example:

“I was working, and we learned that there were going to be layoffs in my company in three months. I did nothing with that time besides worry. I poisoned my life by worrying obsessively, even though I had no control over what would happen. Well — I wish I had those three months back.”

The elders aren’t opposed to rational planning for the future. It’s the free-floating worry, after one has done everything one can about a problem, which seems so wasteful to them.

Joshua Bateman, 74, summed up the consensus view:

“If you’re going to be afraid of something, you really ought to know what it is. At least understand why. Identify it. ‘I’m afraid of X.’ And sometimes you might have good reason. That’s a legitimate concern. And you can plan for it instead of worrying about it.”

In addition to good planning as a cure for worry, the elders also recommend actively working toward acceptance.

“There was a priest that said mass for us, and at a certain time of his life, something happened, and it broke his heart. And he was very angry — he just couldn’t be resigned, he couldn’t get his mind off it. Just couldn’t see why it had happened.

So he went to an elderly priest and said, ‘What shall I do? I can’t get rid of it.’ And the priest said, ‘Every time it comes to your mind, say this.’ And the priest said very slowly, ‘Just let it be, let it be.’ And this priest told us, ‘I tried that and at first it didn’t make any difference, but I kept on. After a while, when I pushed it aside, let it be, it went away. Maybe not entirely, but it was the answer.’ ”

Sister Clare, one of the most serene people I have ever met, has used this technique for well over three-quarters of a century.

“So many things come to your mind. Now, for instance, somebody might hurt your feelings. You’re going to get back at him or her — well, just let it be. Push it away. So I started doing that. I found it the most wonderful thing because everybody has uncharitable thoughts, you can’t help it. Some people get on your nerves and that will be there until you die. But when they start and I find myself thinking, ‘Well, now, she shouldn’t do that. I should tell her that . . .’ Let it be. Often, before I say anything, I think, ‘If I did that, then what?’ And let it be. Oh, so many times I felt grateful that I did nothing. That lesson has helped me an awful lot.”

According to scientists who study worry, its key characteristic is that it takes place in the absence of actual stressors. This kind of worry — ruminating about possible bad things that may happen to us or our loved ones — is entirely different from concrete problem solving. When we worry, we are dwelling on possible threats to ourselves rather than using our cognitive resources to figure a way out of a difficult situation.

According to the elders, planning actively enhances life, whereas down the road worry is deeply regretted as a waste of our all-too-short time on Earth.

Things to Do in Your 20s to Prevent Regrets Later in Life

“People look for retreats for themselves, in the country, by the coast, or in the hills . . . There is nowhere that a person can find a more peaceful and trouble-free retreat than in his own mind. . . . So constantly give yourself this retreat, and renew yourself.”